This invention relates to the field of torque wrenches. More particularly, this invention relates to the field of manually operated torque wrenches in which the potential for drive back or kick back poses a hazard to the operator of the wrench. Even more particularly, this invention relates to an improvement to the torque wrench of U.S. Pat. No. 4,231,454.
U.S. Pat. No. 4,231,454 is owned by the assignee of the present application, and the entire contents of U.S. Pat. No. 4,231,454 are incorporated herein by reference. While wrenches built according to U.S. Pat. No. 4,231,454 are suitable for their intended purpose and are an improvement over the prior art, field experience has revealed the existence of a problem which needs to be corrected. Specifically, field experience has shown that with some wrenches the operation of the slip brake (split ring 50 and sleeve 54) may become erratic. Specifically, the slip brake may hang up or operate in a jumping or chattering manner rather than operating with a smooth rotary motion as is desired when the direction of input force is reversed to relax the torquing load.
It has been determined that the problem with the slip brake of U.S. Pat. No. 4,231,454 is the result of the lack of adequate lubrication between the relatively moveable parts of the slip brake.